Vision systems frequently entail detecting and tracking a subject's eyes in an image generated by a video camera. In the motor vehicle environment, for example, a camera can be used to generate an image of the driver's face, and portions of the image corresponding to the driver's eyes can be analyzed to assess drive gaze or drowsiness. See, for example, the U.S. Pat. Nos. 5,795,306; 5,878,156; 5,926,251; 6,097,295; 6,130,617; 6,243,015; 6,304,187; and 6,571,002, incorporated herein by reference.
Due to variations in ambient lighting, the vision system typically includes a bank of infrared lamps that are lit during the image capture interval of the camera to actively illuminate the driver's face. While such active lighting ensures that the driver's face will be sufficiently illuminated to enable the camera to produce a high quality image, it can also introduce glare that occludes the eye when the driver is wearing eyeglasses. Such eyeglass glare is troublesome because it can interfere with the operation of the vision system's eye detection and tracking algorithms. It may be possible to remove eyeglass glare from an image, but this typically adds a significant amount of image processing, which may be impractical in a system that already is burdened with complex image processing routines. Accordingly, what is needed is a way of producing high quality eye images that are not occluded by eyeglass glare.